Compressor timer

Discussion in 'The Projects Forum' started by soda, Feb 15, 2012.

  1. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    Hi to all,

    All i want the timer to do is to switch on a compressor and when it turn off,the buzzer has to sound for 3 seconds.

    The one moment it does, and the next moment it don't. The buzzer is a bit unpredictable, so why is that?

    I'll appreciate all the help i can get.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Hmmm.......couple of guesses.

    Check relay contact.
    Check buzzer.
    check for loose connection or solder joints.
     
  3. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    Rifaa,

    What about the relay contacts? It's a new relay and every things is working. It's just the buzzer that don't sound every time. It looks more like there's a problem with the mono stable to me,

    If i turn on the circuit for the very first time, every thing is working, but when i want to use the compressor a second time, still wile the power is on, the buzzer doesn't sound.

    Maybe i have to add a reset to it.
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Build the buzzer circuit separately and check
     
  5. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    Rifaa

    I find a similar threat where Bill reply's. I'm gonna follow it and see if he come up with something i can use.It's the thread about the prob.

    So thanks for your help mate
     
  6. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    I would leave IC2 always connected to the power supply and trigger it with the negative edge of the output of IC1.

    You can couple the output of IC1 via a capacitor as in here:
    [​IMG]
     
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    One Q...

    How long does it take to for u to have the compressor off so that the beeper sounds.

    Is it more than 15 mins or more.

    Can u take a voltage measurement while it is operating with a DVM
     
  8. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    This is one of those BAD NEWS circuits. Wiring both your power and control into a little black box is BAD business. Your problems haven't even started yet.
     
  9. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    Rifaa

    The buzzer has to sound immediately(for a few seconds) after the compressor turned off
     
  10. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    I'm not sure if i'm with you here. What about the relay. I still wanted to power on and off the compressor. This is what's it's all about. When the compressor turns off, the buzzer has to sound for a couple of seconds to warn me the compressor stops
     
  11. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    soda ...

    U did not answer my question ?

    Read post 7 and tell me
     
  12. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    Rifaa,

    Sorry mate. I set up ic1 to run at 5, 10 or 15 min. This compressor is to make bubbles in a liquid and it all depends on what time i want the compressor to run on.

    If it's a cold day then you need more time for the ferric chloride to do the job
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    IC..

    Tell me, have u killed any timers lately ?
     
  14. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    [​IMG]Ha,ha! you mean kill with a hammer. Sometimes i really feel like doing it, but as far as i know, no i didn't kill a timer or any other thing.
    Or did you mean kill time. I never kill time because time is always a good thing.
     
  15. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    I really meant it.

    Timer, the 555 IC. ....Has any chip faulted. When the buzzer does not sound.
     
  16. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    The output of IC1 goes to the transistor that turns on the relay AND to the circuit I drew to trigger the second 555 on the negative edge of the output of IC1. (I didn't draw the existing transistor)

    Connect the power supply of IC2 directly to the same power supply of IC1, don't pass it through the relay.
     
  17. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    I didn't do exactly as you said but what i did, was to connect pin8 to the 12v rail as you said.

    Please have a look at my circuit the way I've changed it now. It's working now, so thanks alot for your input. I really appreciate your help

    Some error happen when i try to upload the pic,but i'll do it tomorrow before 12 AM
     
  18. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    No, The 555 is still in a good condition. I've tried to upload my new edited schematic, but some error kicked in so, i'll do it later today. It's working now.

    Many thanks mate
     
  19. soda

    Thread Starter Active Member

    Dec 7, 2008
    174
    13
    This is my working layout of the compressor timer
     
  20. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Is the Cap discharging properly in that manner. ?

    If it cannot discharge then timer won't work in the successive cycles. I think this is why u are getting one time buzzes. It is discharging over time.
     
Loading...